Question 1

What is the difference between probability and odds?

Accepted Answer

Probability is the ratio of favorable outcomes to total outcomes (e.g., 1/6 for rolling a specific number on a die). Odds compare favorable to unfavorable outcomes (e.g., 1:5 for rolling that number, meaning 1 way to succeed vs 5 ways to fail). To convert odds a:b to probability: P = a/(a+b).

Question 2

What is complement probability?

Accepted Answer

The complement of an event A is the event 'not A' (written A' or A-bar). P(A') = 1 - P(A). For example, if the probability of rain is 0.3, the probability of no rain is 1 - 0.3 = 0.7. The complement rule is useful when it is easier to calculate the probability of something NOT happening.

Question 3

Can probability be greater than 1?

Accepted Answer

No. Probability ranges from 0 to 1 (or 0% to 100%). A probability of 0 means the event is impossible, and 1 means it is certain. If your calculation gives a value outside this range, check your inputs -- favorable outcomes cannot exceed total outcomes.

Question 4

What does 'equally likely outcomes' mean?

Accepted Answer

This formula assumes all outcomes have the same chance of occurring (like a fair die or coin). If outcomes are not equally likely (e.g., a loaded die), you cannot simply divide favorable by total. You would need to know the individual probabilities of each outcome.

Probability Calculator

Basic Probability Formula

Complement Rule

Odds vs Probability

Examples

Frequently Asked Questions